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Número de pieza | YB1522 | |
Descripción | Step-up DC-DC Converter White LED Driver | |
Fabricantes | YOBON TECHNOLOGIES | |
Logotipo | ||
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YB1522
Step-up DC-DC Converter White LED Driver
Description
The YB1522 is a step-up DC-DC converter;
with wide input voltage range from 3V to
16V, which operates as current source to
drive up to 3S7P to 3S10P (VIN at 3V to
5V). Series connecting of the LEDs
provides identical LED currents resulting in
uniform brightness and eliminating the
need for ballast resistors. The light intensity
of these LEDs is proportional to the current
passing through them. The YB1522
switches at a fixed frequency of ~930KHz,
allowing the use of tiny, low profile
inductors and capacitors to minimize
footprint and cost in space consideration
applications.
The YB1522 can drive up to 3S10P white
LEDs from a single Li-Ion battery. At
automotive (5V/12V) applications with
higher conversion efficiency. To control
LED brightness, the LED current can be
pulsed by applying a PWM (pulse width
modulated) signal with a frequency range
of 100Hz to 1KHz to the CTRL pin.
YB1522 has integrated Latched Over
Voltage Protection that prevents damage to
the device in case of a high impedance
output due to faulty LED or open circuit
caused by abnormal conditions.
Features
Built-in Internal Switch
3V to 16V Input Range
<1uA Shutdown Current
High Efficiency
Internal Soft Start
Drives up to 3S7P to 3S10P White
LEDs(VIN at 3.5V to 5V)
Over Voltage Protection 30V
Small 5-Lead SOT-23 Package
Analog and PWM Dimming Control
100mV Low Reference Voltage
Applications
5” ~ 7” LCD Display Module
White LED Backlighting
Car TV
Handheld and PDA
Electronic Books
Digital Photo Frame
Typical Application Circuit
YB1522 Rev.1.0
Figure 1: Typical Application Circuit
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1
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YB1522
Step-up DC-DC Converter White LED Driver
C1=1uF/16V
L1=33uH/CD43
C2=10uF/16V
R1=0.62Ω
Output Waveform
Output Ripple
Vin & Efficiency
88%
86%
84%
82%
80%
78%
76%
74%
72%
2.5 3 3.5 4 4.5 5 5.5 6
Vin(V)
Vin & Iout
250
200
150
100
50
0
2.5 3 3.5 4 4.5 5 5.5 6
Vin(V)
YB1522 Rev.1.0
www.yobon.com.tw
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YB1522
Step-up DC-DC Converter White LED Driver
Over Voltage Protection
The YB1522 has an internal over voltage
protection circuit which also acts as an
open-circuit protection. In the cases of
open circuit or the LEDs failure, the LEDs
are disconnected from the circuit, and the
feedback voltage will be zero. The YB1522
will then switch to a high duty cycle
resulting in a high output voltage, which
may cause SW pin voltage to exceed its
maximum 30V rating. The YB1522 will
shutdown automatically until input condition
changes to bring it out of the shutdown
mode.
Inductor Selection
A 33uH inductor is recommended for most
applications to drive more than 3x7 WLEDs.
Although small size and high efficiency are
major concerns, the inductor should have
low core losses at 1MHz and low DCR
(copper wire resistance).
Diode Selection
To maintain high efficiency, the average
current rating of the Schottky diode should
be large than the peak inductor current, IPK.
Schottky diode with a low forward drop and
fast switching speeds are ideal for increase
efficiency in portable application. Choose a
reverse breakdown of the Schottky diode
large than the output voltage.
Capacitor Selection
Choose low ESR capacitors for the output
to minimize output voltage ripple. Multilayer
capacitors are a good choice for this as well.
A 10uF capacitor is sufficient for 3x7
WLEDs applications. For additional
bypassing, a 100nF ceramic capacitor can
be used to shunt high frequency ripple on
the input.
The input bypass capacitor CIN, as shown
in Figure 1, must be placed close to the IC.
This will reduce copper trace resistance
which affects input voltage ripple of the IC.
For additional input voltage filtering, a
100nF bypass capacitor can be placed in
parallel with CIN to shunt any high
frequency noise to ground. The output
capacitor, COUT, should also be placed
close to the IC. Any copper trace
connections for the COUT capacitor can
increase the series resistance, which
directly effect output voltage ripple.
The feedback network, resister R2 should
be kept close to the FB pin to minimize
copper trace connections that can inject
noise into the system. The ground
connection for the feedback resistor
network should connect directly to an
analog ground plane. The analog ground
plane should tie directly to the GND pin. If
no analog ground plane is available, the
ground connection for the feedback
network should tie directly to the GND pin.
Trace connections made to the inductor
and Schottky diode should be minimized to
reduce power dissipation and increase
overall efficiency.
YB1522 Rev.1.0
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11 Page |
Páginas | Total 12 Páginas | |
PDF Descargar | [ Datasheet YB1522.PDF ] |
Número de pieza | Descripción | Fabricantes |
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YB1522 | Step-up DC-DC Converter White LED Driver | YOBON TECHNOLOGIES |
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